Insulating cover



' CROSS REFERENCE flwvnum Feb. 1949- w. M. CHARMAN :rm. 2,462,255

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mmvrm fie 2 Mug-u M CHAPMAN Bans/mm E Arm-ran 14444 W W gfllm firmer/n5\a Y I \m-L L Patented Feb. 22, 1949 8.402.255 msuulmo COVER Walter M.Charman. Shaker Heights. and Benjalnln F. Anthony, Cleveland Heights.Ohio. as signors to Ferro Engineering Company, Cieveknd. Ohio. acorporation of Ohio Application July 28, 1945. Serial No. 807.590

I Claims. (Cl. 22-141) Insulating coverings for ingot sinkheads. feedheads. or risers have been in use to some extent for many years. Variousmaterials, both combustible and incombustible. have been suggested forthe purpose. oftentimes loose or bulk material, has been shoveled uponthe surface of the metal to be insulated. Sometimes covers in the formof monolithic or slab-like bodies have been tiled. and in some casessuch slabs have been shaped and dimensioned to approximate the area ofhot metal to be covered, In all cases as heretofore practiced in the artthe material, whether in bulk or slab form. deposited upon the hot metalin order to coverthe same with a blanket of suineient thickness toconstitute satisfactory insulation. must be bulky. Hence it occupiesconsiderable space in shipping and storage. vFurthermore, coveringsemploying many of the materials heretofore used for the purpose suffercontraction or shrinkage when subiected to the intense heat of themetal. This. with its consequent lessening of insulation, must either beaccepted or counteracted by additional applications of the material.Where slabs have been used in upwardly tapering hot tops they havenecessarily been made small enough to clear the upper end of the hot topp ning. which is smaller than the area of metal at the top of thesinkhead. Accordingly the slab in such cases has not completely coveredthe hot metal.

- The present invention overcomes the difiicultles above mentioned, andprovides insulation at least equal in effectiveness to anythingpreviously known.

One of the objects of the invention is the provision of a covering thatis created .in situ from material which, when first deposited upon thehot metal. occupies a space of much less volume than that occupied bythecovering when completed by the action of the heat.

Another object is the provision of a covering in the form of a slab of asize to readily enter the opening at the top of a hot top. where thematerial of the slab when subjected to the heat of the molten metal willexpand laterally as well as upwardly and fill the cavity in the hot topabove the metal to a depth to insure good insulation.

A further object is the provision of means for creating a cover in situby the expansion under the influence of heat of an exfoliating material,especially an exfoliating material mixed with a combustible material.the latter being distributed 2 evenly throughout the cover and itscombustion assisting the heat of the molten metal in etfectingexfoliation. particularly of the exfoliating material in the upperportions of the cover which, of course, are farthest from the hot metal,

Other objects and features of novelty will appear as we proceed with thedescription of those embodiments of the invention which. for thepurposes of the present application. we have illustrated in theaccompanying drawing, in which Figs. 1 and 2 are diagrammaticperspective views illustrating two somewhat different forms of coverslab embodying the invention.

This invention has to do with the use of insulating coverings forsolidifying castings. comprising materials which will expand whensubjected to the high temperatures of the castings, either when suchmaterials are used by themselves or in combination with othercombustible or incombustible materials.

Expanding materials for the purpose of this invention may be natural ormanufactured. Of natural materials perlite. a volcanic glass capable ofexpanding to six or seven times its original size is an example, butvermiculite, a secondary mineral formed by alteration of biotite andphlogopite mica. found scattered about the world. and capable in someforms of exfoliating up to twenty times its original size, is preferredat the present time. Amongst the manufactured expanding materials may bementioned pyrotechnics such as Pharaoh's eggs and the well-known Fourthof July serpents, these materials being capable of expanding to ten orfifteen times their original size. We prefer to employ vermiculite.

Micaceous vermiculite ore may be obtained in relatively small particles.In its natural state each vermiculite particle has the appearance of aflake, but when heated sumciently these flakes expand into a conditionin which each one resembles a tiny accordion. A given quantity of thematerial in its natural state, when expanded by the action of heat,occupies a space many times greater than when unexpanded, the ore of No,3 quality. which is readily obtainable in suflicient quantities,expanding to the extent of eight to twelve times its original volume.The fact that it may be shipped in its unexpanded low volume state andmay be converted in'situ to its high volume condition, obviously is ofgreat practical importance from the standpoints of transportation, plantstorage facilities and handling.

For the purposes of the present invention. vermiculite ore. the No. 1grade preferably. may be used as a covering either by itself or combineda I l 3 with materials of neutral or exothermic properties to form abulk mixture. In either state the bulk covering material may be shoveledonto the metal surface to be insulated or thrown over its surface from ameasuring container. Alternatively. the loose material may be packed incombustible containers. such as cardboard or paper. designed to hold apredetermined quantity, and such container deposited upon the hot ingot.

ainkhead or riser surface.

While the use of bulk material is entirely practical and may bepreferable in some instances. it is desirable in many cases to preparethe material in slab form. for then it can be handled quickly and easilyand the exact amount of vermiculite required for each ingot can bereadily incorporated in the slab. The slabs are made preferably to ashape approximately the same as that of the opening in a given hot top.but of slightly smaller dimensions in order that they may be readilyinserted through the opening. They may be made as thin as strength forstoring and handling will permit. this being dependent partly of courseupon the size of the slab. Wire reenforcement may be used if desired.

In Fig. i we have illustrated a slab comprising surface layers iii ofpaperboard to the inner surfaces of which glue or other adhesive ii isapplied freely. Between these surfaces there is a thin layer is ofvermiculite in its natural state. the adhesive ll holding it in place.Alternatively. the adhesive and vermiculite may be mixed together andapplied as a paste on an uncoated paperboard layer II and the otherlayer III then applied above the pasted layer. More or less pressure andsome degree of heat insufficient to cause exfoliation oi vermiculite maybe used to cause the elements of this sandwich to adhere firmly. Insteadof a sandwich like slab. a slab may be made by coating one or bothsurfaces of paperboard with vermiculite ore and adhesive. Pig. 2 of thedrawing represents a monolithic slab which may be molded to whatevershape is required or may be formed in large sheets and cut to thedesired shape and size. The constituents for the mix from which suchslabs are made may vary considerably. vermiculite or other heatexpansible material constituting one of the ingredients in each case.Sumcient thickness for strength is obtained by the use of a filler and abonding agent. Any one of many different fillers may be employed. andthey may be either neutral or exothermic. As useful inert fillers theremay be mentioned slag, rock wool. sand. clay. ashes and crushed brick.Exothermic fillers should be slow burning or charring such as coal.coke, sawdust, hulls. stalks. straws or any combustible wastage. At thepresent time we prefer sawdust. particularly sawdust containing a largepercentage of wood fibers.

As a bonding agent we prefer to employ a material which will be weakenedor destroyed when the cover is subjected to the heat of the ingot.Otherwise the expansion of the vermiculite or its equivalent will behindered. Clay. especially bentonite. is a good bonding agent eitheralone or in combination with sodium silicate. A land filler with cementand water as the bonding agent has also been found to be satisfactory.Various other binders and combinations of binders have been found to beusable. as for example dextrin. corn flour. goulac and core oil, and webelieve that still others such as gelatins, caseins. gums, resins andwaxes would be suitable for the purpose. No binder should be employedwhich requires heat for setting above that at which exioliation ofvermiculite takes place.

After the molding of the slab is completed. it should be dried quitethoroughly. Temperatures of 200 or 300 F. may be safely employed fordrying. as there is no material exfoliation of vermiculite at thosetemperatures.

Slabs are convenient from the standpoints of shipping. handling andmeasuring the component constituents. They need not exactly fit theopening to be covered, and the expanding of the swelling agenteffectively seals all clearances. Filler shrinkage is more thancompensated by the exfoliation. and a complete cover and insulation isthereby obtained. Slabs can be coated for waterproofing and can bepacked in quantities to be opened as needed. A limited number of slabsizes for a greater number of sizes of sinkhead areas is suflicient. aslateral expansion during exfoliation compensates for clearancedifferences. It is also possible to lay slabs across the opening of amold, hot top or feed head. and allow radiant heat to destroy the bond.exfoliate the vegan; lite and permit the covering to sink to the metalmeta sur cc to be insulated.

As a further alternative, the swelling agent may be suspended in a heavyviscous liquid. the proper quantity of which may be poured onto thesurface of the casting. the liquid nature of the material causing it tospread evenly over the ingot preparatory to exfoliation. Such a liquidshould be combustible but not explosively combustible. Oils and tarcompounds which are of such consistency that they may be poured freelyare suitable for the purpose. The liquid used must be heavy enough ofcourse that after agitation it will hold the vermiculite in suspensionwhile it is being poured over the ingot.

The use of our method in connection with the casting of metal ingots.for example. will be evident from the foregoing description. The ingotis poured. with a sinkhead in case a hot top is employed on the mold.More or less promptly thereafter a slab of the proper size is droppedupon the molten or crusted surface of the metal, whereupon exfoliationbegins immediately accompanied by combustion if combustible filler ispresent in the slab. Combustion and exfoliation take place gradually butare completed in a relatively short time. about 15 minutes maximum.accompanied by a swelling and expanding of the slab material until acomplete blanket of insulation is formed several times thicker than theoriginal slab depending upon the amount of vermiculite present. Whereloose or bulk material is employed instead of a preformed slab theproper quantity of such material is shoveled or otherwise deposited uponthe metal. exfoliation and swelling with combustion of any combustiblematerial present taking place in much the same manner as when thematerial is used in slab form.

Having thus described our inventiomwe claim:

1. The method of creating in situ an insulating blanket for asolidifying casting. which comprises placing over the hot metal acovering comprising noncombustible material of the group consisting ofvermiculite and perllte of a character to expand permanently under theinfluence of heat from the casting to occupy a space at least five timesthat occupied by the material when deposited.

2. The method of creating in situ an insulating l itaeasss blanket for asolidifying casting. which comprises g over the hot metal a coveringcomprising vermiculite in its unexpanded state to produce a porousblanket under exfoliation due to heat from the casting.

l. The method of creatins in situ an insulatins blanket for asolidifying casting. which comprises placing over the hot metal acovering of vermiculite in its unexpanded state combined withcombustible particles, exfoliation of the vermiculite under theinfluence of heat from the casting and from the combustion of thecombustible particles causing said covering to expand.

4. The method of creating in situ an insulating blanket for asolidifying casting. which comprises placina over the hot metal acovering of vermiculite in its unexpanded state and combustibleparticles intimately commingled. exfoliation of the vermiculite underthe influence of heat from the casting and from the combustion of thesaid combustible particles causing said covering to expand gradually.

9. The method of creating in situ an insulating blanket for asolidifying casting. which comprises placing over the hot metal a formedbody through which vemicuiite in its unexpanded state is distributcd.the said bodybeing of smaller horisontal dimensions than the area ofexposed hot metal. exfoliation of the vermiculite due to heat from thecasting swelling the said body and causing its material to expandlaterally as well as verticall! and thus to completely cover the hotmetal.

6. An insulating body for a solidifying casting. which comprisesvermiculite in its unexpanded state; a combustible filler. and a bondingagent formed. and dried.

7. An insulating body for a solidifying casting which comprisesvermiculite in its unexpanded state. a combustible filler and a bondingagent all intimately eommingied. formed and dried.

8. An insulating body for a solidifying casting. which comprisesvermiculite in its unexpanded state. sawdust. and a bonding agentformed. and dried.

9. An insulatins body for a solidifying casting which comprisesvermiculite in its unexpanded state. sawdust. and a bonding agent allintimately commingied. compacted and dried.

WALTER M. CHARMAN. BENJAMIN I". ANTHONY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 929.688 Monnot Aug. 8. 1909 as1.715.977 Bates June 4. 1929 1.920.854 Gathmann Aux. 1. 1933 2.090.490l-iawiey Aug. 17. 1937 2.110.470 Norton Mar. 8. 1939 2.165.945 BeaverJuly ll. 1939 2,148,583 Rowe Feb. 28. 1939 2.218.965 Young Oct. 22. 19402.250.009 Coble July 22. 1941 2.390.732 Page Dec. 11. 1945 Certificateof Correction Patent NO. 3,462,255. February 22, 1949.

WALTER M. CHARMAN ET AL.

It is hereby certified that the above numbered patent was erroneouslyissued to Ferro Engineerin conwl pany, as assignee of the ent reinterest, whereas said patent should have issue to alter M. Charman, andBen emin F. Anthon said Anthony asslgnor to Form Engineering Company, asshown by the record 0 assignments in In the ant, line 14, for "FormEngineering Company, its successors read Walter M. (fihrman, his heirsor assigns, and Farm Engineering Company, its succesms; and that the andLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office:

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Am'atant Commissioner of Patents.

